Sepsis-Induced Disruption in Parathormone-Cholecalciferol-Calcium Axis in Children from a Lower Middle-Income Country: A Prospective Observational Study

Background Sepsis disrupts parathormone-cholecalciferol-calcium (PCC) axis. However, comprehensive longitudinal data from LMICs remain scarce. We aimed to characterize these disruptions and explore their correlation with critical care needs and outcomes in pediatric septic shock. Methods 25-hydroxycholecalciferol [25(OH)D], parathormone, corrected total and ionized calcium (cTCa and iCa ⁺⁺ ) were measured among children with septic shock (6mo-12yrs; n = 69) in a prospective observational study. 25(OH)D and parathormone were measured on day (D) 1 and D7, while cTCa and iCa ⁺⁺ were measured on D1, D4, D7, and D10. Levels and their trends over 10 days were compared between survivors and non-survivors. Correlation between D1 levels and illness severity indicators, resuscitation requirements, and outcomes was assessed. Results Eighteen (26.1%) patients were undernourished; mortality was 37.7% (26/69). Vitamin D insufficiency was common; 81.2% had 25(OH)D < 20ng/mL on D1, including 55.1% with deficiency (< 12ng/mL). Non-survivors had lower 25(OH)D on D1 and showed a sharp paradoxical rise on D7. Parathormone was elevated in 44.1% patients, with significantly higher levels among non-survivors on D1 and D7. Hypocalcemia was common (30.5% by cTCa; 59.4% by iCa ⁺⁺ ). Non-survivors had lower cTCa on D1 that persisted over 10 days, whereas it gradually rose in survivors. Lower 25(OH)D and higher parathormone correlated with greater illness severity scores. Higher parathormone and lower calcium levels were associated with greater resuscitative requirements; the former was also correlated with poor clinical outcomes. A level > 53pg/mL predicted mortality (AUC, 0.662; p = 0.019). Conclusions Findings demonstrate a high burden of hypovitaminosis D, hypocalcemia, and marked disruption in PCC axis in pediatric septic shock, including persistent lower calcium levels despite continued secondary hyperparathyroidism among non-survivors. These disruptions were correlated with greater illness severity, higher critical care needs, and a poor prognosis. These derangements justify trials of vitamin D replacement, with or without calcium, for pediatric septic shock in LMICs.